Ribosome biogenesis is one of the most fundamental of cellular processes because without ribosomes cells cease growing. In metazoan cells, ribosome biogenesis is cell cycle regulated, as both transcription and processing of ribosomes ceases during mitosis (Dundr, 1998; Sirri, 2000). Currently, little else known about the connection between ribosome biogenesis and the cell cycle. Using yeast as a model system, first I plan to determine whether ribosome biogenesis is cell cycle regulated. Second, I will determine whetheNanl/Utpl 7 may provide a regulatory link between these two processes. Nanl/Utpl7, Net 1 associated nucleolarprotein, was originally purified as a component of the RENT complex, Regulator of Nuclealor Silencing and Telophase, which is important for mitotic exit (Shou, 1999). It has also been purified as a component of the newly purified SSU processome, where it affects processing of 18S ribosomal subunits (Dragon et al., Submitted). Therefore, Nanl/Utpl7 may provide a link between these two processes. Finally, I will determine whether there are a critical number of ribosomes needed for growth and division. In studying the link between these two fundamental processes, I will be able to understand how abnormal cell growth and ribosome synthesis are directly connected, such as in the case of human cancers.